Editing GC-content (section)

==Applications==
=== Molecular biology ===
In [[polymerase chain reaction]] (PCR) experiments, the GC-content of short oligonucleotides known as [[primer (molecular biology)|primers]] is often used to predict their [[polymerase chain reaction|annealing temperature]] to the template DNA. A higher GC-content level indicates a relatively higher melting temperature.

Many sequencing technologies, such as [[Illumina sequencing]], have trouble reading high-GC-content sequences. [[Bird]] genomes are known to have many such parts, causing the problem of "missing genes" expected to be present from evolution and phenotype but never sequenced — until improved methods were used.<ref>{{cite journal|vauthors=Huttener R, Thorrez L, Veld TI |display-authors=etal|title=Sequencing refractory regions in bird genomes are hotspots for accelerated protein evolution|journal=BMC Ecol Evol|volume=21|issue=176|year=2021|page=176 |doi=10.1186/s12862-021-01905-7|pmid=34537008 |pmc=8449477 |doi-access=free}}</ref>

=== Systematics  ===
The [[species problem]] in non-eukaryotic taxonomy has led to various suggestions in classifying bacteria, and the ''ad hoc committee on reconciliation of approaches to bacterial systematics'' of 1987 has recommended use of GC-ratios in higher-level hierarchical classification.<ref>{{cite journal |doi=10.1099/00207713-37-4-463 |author=Wayne LG |title=Report of the ad hoc committee on reconciliation of approaches to bacterial systematic |journal=International Journal of Systematic Bacteriology |volume=37 |issue=4 |pages=463–4 |year=1987|display-authors=etal|doi-access=free }}</ref> For example, the [[Actinomycetota]] are characterised as "high GC-content [[bacterium|bacteria]]".<ref>[https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=1760&lvl=3&lin=f&keep=1&srchmode=1&unlock Taxonomy browser on NCBI]</ref> In ''[[Streptomyces coelicolor]]'' A3(2), GC-content is 72%.<ref>[https://www.ncbi.nlm.nih.gov/sites/entrez?db=genomeprj&cmd=Retrieve&dopt=Overview&list_uids=242 Whole genome data of ''Streptomyces coelicolor'' A3(2) on NCBI]</ref> With the use of more reliable, modern methods of molecular systematics, the GC-content definition of Actinomycetota has been abolished and low-GC bacteria of this [[clade]] have been found.<ref name="lowGCActinoacteria">{{cite journal |vauthors=Ghai R, McMahon KD, Rodriguez-Valera F |title=Breaking a paradigm: Cosmopolitan and abundant freshwater actinobacteria are low GC |journal=Environmental Microbiology Reports |volume=4 |issue=1 |pages=29–35 |year=2012 |doi=10.1111/j.1758-2229.2011.00274.x |pmid=23757226|bibcode=2012EnvMR...4...29G }}</ref>